Primary transmission of the disease occurs from infected potatoes. Dormant mycelium becomes active on seedlings from diseased potatoes. Conidiophores are produced from the mycelium of the fungus. Conidia are produced in conidiophores. Conidia spread with water and wind and invade new plants.
Outbreaks of this disease are seen in Asia, North America, Europe, Caribbean Islands, Oceania, Australia, Fiji, New Caledonia, New Zealand and Papua New Guinea. If the temperature is very low in winter, there is a possibility of this disease in Bangladesh.